IBM RS/6000 - Manual (Page 29)

Portables
Medialess
Desktop
Workstations
Servers
Because PReP requires machine abstractions, the specification accommodates the
evolution of software and hardware technologies without losing system
compatibility.
The PReP specification covers:
Hardware Configuration
The hardware configuration defines the minimum and recommended
hardware standards and capacities required to be PowerPC Reference
Platform-compliant and compatible with targeted operating
environments.
Architecture
The system architecture defines the minimum and recommended system
attributes required to design a compatible computer system. This
section describes the key hardware and software architecture attributes
and restrictions defined for PReP compliance.
Machine Abstraction
To enable the same operating system to run on different
PReP-compliant platforms, the operating system must be designed to
use
abstraction software to interface with the hardware.
Abstraction software concentrates operating system
hardware-dependent code into a collection of code that has well-defined
interfaces with the operating system kernel and may be modified to
meet the hardware interface.
Boot Process
This section describes the boot process, the format and the contents of
boot information, and the state of the system at the end of the boot
process. It also mentions “Open Firmware,” the IEEE standard P1275
for Boot Firmware, as the goal for a PReP-compliant firmware
implementation.
Open Firmware is defined in one of the appendixes included in the
specification.
Reference Implementation
The PReP specification describes a reference implementation of a
PReP-compliant system. This description may be used as a high-level
design for vendors waiting to produce a compatible system, or it may be
used as an example for vendors who want to produce a different
system.
Power Management
Power Management is used for saving electronic power. There are two
types of Power Management techniques:
Micro Power Management
This is hardware-managed power control.
Chapter 1. Introduction 5